Using site-specific nitrogen management in rainfed corn to reduce the risk of nitrate leaching

Abstract

Managing nitrogen (N) to achieve yield potential and limit losses to the environment is challenging due to the temporal and spatial variability in crop N uptake which affects the distribution of soil-N. Nitrogen fertilization using site-specific management (SSM) is one of a number of strategies that can improve the efficiency of N use and reduce the losses of N to the environment from cropping systems. The aim was to assess: (i) corn (Zea mays L.) grain yield and N uptake; and (ii) soil residual- and potentially leachable-N, and its relationship with N and water use efficiency using SSM vs. uniform management (UM) strategies in high-(HP) and low-(LP) productivity zones on soils of the Inland Pampas of Argentina. Differences in soil residual- and potentially leachable-N, corn grain yield, N uptake, water and N use efficiency were compared between treatments. In HP-zones, corn grain yield and total biomass were 2.7 and 4.2 Mg ha−1 higher with SSM than UM, and corn grain N uptake and total N uptake increased by 21% and 18% with SSM when compared to UM. Soil residual-N at field-scale was reduced by 18% with SSM. Marginal differences in potentially leachable-N among treatments were observed throughout the soil profile; the highest nitrate concentration was 6.6 mg kg−1 in LP-zones with UM within the 210–240 cm soil layer. Overall corn water use efficiency in total biomass was 16% higher with SSM than with UM in both LP- and HP-zones. Using SSM in the LP-zones increased corn N use efficiency in grain and total biomass by 50% and 43% respectively. In this context, SSM can be considered as a conservation practice that optimizes N and water use efficiency by corn under dry conditions.